When we finish a zfs receive, dmu_recv_end_sync() calls
zvol_create_minors(async=TRUE). This kicks off some other threads that
create the minor device nodes (in /dev/zvol/poolname/...). These async
threads call zvol_prefetch_minors_impl() and zvol_create_minor(), which
both call dmu_objset_own(), which puts a "long hold" on the dataset.
Since the zvol minor node creation is asynchronous, this can happen
after the `ZFS_IOC_RECV[_NEW]` ioctl and `zfs receive` process have
completed.
After the first receive ioctl has completed, userland may attempt to do
another receive into the same dataset (e.g. the next incremental
stream). This second receive and the asynchronous minor node creation
can interfere with one another in several different ways, because they
both require exclusive access to the dataset:
1. When the second receive is finishing up, dmu_recv_end_check() does
dsl_dataset_handoff_check(), which can fail with EBUSY if the async
minor node creation already has a "long hold" on this dataset. This
causes the 2nd receive to fail.
2. The async udev rule can fail if zvol_id and/or systemd-udevd try to
open the device while the the second receive's async attempt at minor
node creation owns the dataset (via zvol_prefetch_minors_impl). This
causes the minor node (/dev/zd*) to exist, but the udev-generated
/dev/zvol/... to not exist.
3. The async minor node creation can silently fail with EBUSY if the
first receive's zvol_create_minor() trys to own the dataset while the
second receive's zvol_prefetch_minors_impl already owns the dataset.
To address these problems, this change synchronously creates the minor
node. To avoid the lock ordering problems that the asynchrony was
introduced to fix (see #3681), we create the minor nodes from open
context, with no locks held, rather than from syncing contex as was
originally done.
Implementation notes:
We generally do not need to traverse children or prefetch anything (e.g.
when running the recv, snapshot, create, or clone subcommands of zfs).
We only need recursion when importing/opening a pool and when loading
encryption keys. The existing recursive, asynchronous, prefetching code
is preserved for use in these cases.
Channel programs may need to create zvol minor nodes, when creating a
snapshot of a zvol with the snapdev property set. We figure out what
snapshots are created when running the LUA program in syncing context.
In this case we need to remember what snapshots were created, and then
try to create their minor nodes from open context, after the LUA code
has completed.
There are additional zvol use cases that asynchronously own the dataset,
which can cause similar problems. E.g. changing the volmode or snapdev
properties. These are less problematic because they are not recursive
and don't touch datasets that are not involved in the operation, there
is still potential for interference with subsequent operations. In the
future, these cases should be similarly converted to create the zvol
minor node synchronously from open context.
The async tasks of removing and renaming minors do not own the objset,
so they do not have this problem. However, it may make sense to also
convert these operations to happen synchronously from open context, in
the future.
Reviewed-by: Paul Dagnelie <pcd@delphix.com>
Reviewed-by: Prakash Surya <prakash.surya@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Matthew Ahrens <mahrens@delphix.com>
External-issue: DLPX-65948
Closes#7863Closes#9885
This logic is not platform dependent and should reside in the
common code.
Reviewed-by: Igor Kozhukhov <igor@dilos.org>
Reviewed-by: Jorgen Lundman <lundman@lundman.net>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Matt Macy <mmacy@FreeBSD.org>
Closes#9505
In the FreeBSD kernel the strdup signature is:
```
char *strdup(const char *__restrict, struct malloc_type *);
```
It's unfortunate that the developers have chosen to change
the signature of libc functions - but it's what I have to
deal with.
Reviewed-by: Jorgen Lundman <lundman@lundman.net>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Matt Macy <mmacy@FreeBSD.org>
Closes#9433
A rangelock KPI already exists on FreeBSD. Add a zfs_ prefix as
per our convention to prevent any conflict with existing symbols.
Reviewed-by: Igor Kozhukhov <igor@dilos.org>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Matt Macy <mmacy@FreeBSD.org>
Closes#9402
We've seen cases where after creating a ZVOL, the ZVOL device node in
"/dev" isn't generated after 20 seconds of waiting, which is the point
at which our applications gives up on waiting and reports an error.
The workload when this occurs is to "refresh" 400+ ZVOLs roughly at the
same time, based on a policy set by the user. This refresh operation
will destroy the ZVOL, and re-create it based on a snapshot.
When this occurs, we see many hundreds of entries on the "z_zvol" taskq
(based on inspection of the /proc/spl/taskq-all file). Many of the
entries on the taskq end up in the "zvol_remove_minors_impl" function,
and I've measured the latency of that function:
Function = zvol_remove_minors_impl
msecs : count distribution
0 -> 1 : 0 | |
2 -> 3 : 0 | |
4 -> 7 : 1 | |
8 -> 15 : 0 | |
16 -> 31 : 0 | |
32 -> 63 : 0 | |
64 -> 127 : 1 | |
128 -> 255 : 45 |****************************************|
256 -> 511 : 5 |**** |
That data is from a 10 second sample, using the BCC "funclatency" tool.
As we can see, in this 10 second sample, most calls took 128ms at a
minimum. Thus, some basic math tells us that in any 20 second interval,
we could only process at most about 150 removals, which is much less
than the 400+ that'll occur based on the workload.
As a result of this, and since all ZVOL minor operations will go through
the single threaded "z_zvol" taskq, the latency for creating a single
ZVOL device can be unreasonably large due to other ZVOL activity on the
system. In our case, it's large enough to cause the application to
generate an error and fail the operation.
When profiling the "zvol_remove_minors_impl" function, I saw that most
of the time in the function was spent off-cpu, blocked in the function
"taskq_wait_outstanding". How this works, is "zvol_remove_minors_impl"
will dispatch calls to "zvol_free" using the "system_taskq", and then
the "taskq_wait_outstanding" function is used to wait for all of those
dispatched calls to occur before "zvol_remove_minors_impl" will return.
As far as I can tell, "zvol_remove_minors_impl" doesn't necessarily have
to wait for all calls to "zvol_free" to occur before it returns. Thus,
this change removes the call to "taskq_wait_oustanding", so that calls
to "zvol_free" don't affect the latency of "zvol_remove_minors_impl".
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: John Gallagher <john.gallagher@delphix.com>
Signed-off-by: Prakash Surya <prakash.surya@delphix.com>
Closes#9380
Refactor the zvol in to platform dependent and independent bits.
Reviewed-by: Allan Jude <allanjude@freebsd.org>
Reviewed-by: Jorgen Lundman <lundman@lundman.net>
Reviewed-by: Igor Kozhukhov <igor@dilos.org>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Matt Macy <mmacy@FreeBSD.org>
Closes#9295
Reviewed-by: Matt Ahrens <matt@delphix.com>
Reviewed-by: Ryan Moeller <ryan@ixsystems.com>
Reviewed-by: Richard Laager <rlaager@wiktel.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Andrea Gelmini <andrea.gelmini@gelma.net>
Closes#9240
When exporting ZVOLs as SCSI LUNs, by default Windows will not
issue them UNMAP commands. This reduces storage efficiency in
many cases.
We add the SCSI_PASSTHROUGH flag to the zvol's device queue,
which lets the SCSI target logic know that it can handle SCSI
commands.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: John Gallagher <john.gallagher@delphix.com>
Signed-off-by: Paul Dagnelie <pcd@delphix.com>
Closes#8933
We've observed that on some highly fragmented pools, most metaslab
allocations are small (~2-8KB), but there are some large, 128K
allocations. The large allocations are for ZIL blocks. If there is a
lot of fragmentation, the large allocations can be hard to satisfy.
The most common impact of this is that we need to check (and thus load)
lots of metaslabs from the ZIL allocation code path, causing sync writes
to wait for metaslabs to load, which can take a second or more. In the
worst case, we may not be able to satisfy the allocation, in which case
the ZIL will resort to txg_wait_synced() to ensure the change is on
disk.
To provide a workaround for this, this change adds a tunable that can
reduce the size of ZIL blocks.
External-issue: DLPX-61719
Reviewed-by: George Wilson <george.wilson@delphix.com>
Reviewed-by: Paul Dagnelie <pcd@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Matthew Ahrens <mahrens@delphix.com>
Closes#8865
Commit 98bb45e resolved a deadlock which could occur when
handling a page fault in zfs_write(). This change added
the uio_fault_disable field to the uio structure but failed
to initialize it to B_FALSE. This uninitialized field would
cause uiomove_iov() to call __copy_from_user_inatomic()
instead of copy_from_user() resulting in unexpected EFAULTs.
Resolve the issue by fully initializing the uio, and clearing
the uio_fault_disable flags after it's used in zfs_write().
Additionally, reorder the uio_t field assignments to match
the order the fields are declared in the structure.
Reviewed-by: Chunwei Chen <tuxoko@gmail.com>
Reviewed-by: Richard Laager <rlaager@wiktel.com>
Reviewed-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#8640Closes#8719
The kernel function which adds new zvols as disks to the system,
add_disk(), briefly opens and closes the zvol as part of its work.
Closing a zvol involves waiting for two txgs to sync. This, combined
with the fact that the taskq processing new zvols is single threaded,
makes this processing new zvols slow.
Waiting for these txgs to sync is only necessary if the zvol has been
written to, which is not the case during add_disk(). This change adds
tracking of whether a zvol has been written to so that we can skip the
txg_wait_synced() calls when they are unnecessary.
This change also fixes the flags passed to blkdev_get_by_path() by
vdev_disk_open() to be FMODE_READ | FMODE_WRITE | FMODE_EXCL instead of
just FMODE_EXCL. The flags were being incorrectly calculated because
we were using the wrong version of vdev_bdev_mode().
Reviewed-by: George Wilson <george.wilson@delphix.com>
Reviewed-by: Serapheim Dimitropoulos <serapheim@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: John Gallagher <john.gallagher@delphix.com>
Closes#8526Closes#8615
The SCST driver (SCSI target driver implementation) and possibly
others may issue read bio's with a length of zero bytes. Although
this is unusual, such bio's issued under certain condition can cause
kernel oops, due to how rangelock is implemented.
rangelock_add_reader() is not made to handle overlap of two (or more)
ranges from read bio's with the same offset when one of them has size
of 0, even though they conceptually overlap. Allowing them to enter
rangelock results in kernel oops by dereferencing invalid pointer,
or assertion failure on AVL tree manipulation with debug enabled
kernel module.
For example, this happens when read bio whose (offset, size) is
(0, 0) enters rangelock followed by another read bio with (0, 4096)
when (0, 0) rangelock is still locked, when there are no pending
write bio's. It can also happen with reverse order, which is (0, N)
followed by (0, 0) when (0, N) is still locked. More details
mentioned in #8379.
Kernel Oops on ->make_request_fn() of ZFS volume
https://github.com/zfsonlinux/zfs/issues/8379
Prevent this by returning bio with size 0 as success without entering
rangelock. This has been done for write bio after checking flusher
bio case (though not for the same reason), but not for read bio.
Reviewed-by: Alek Pinchuk <apinchuk@datto.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tomohiro Kusumi <kusumi.tomohiro@osnexus.com>
Closes#8379Closes#8401
5d43cc9a59 renamed it to rangelock_enter().
Reviewed-by: Matt Ahrens <mahrens@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tomohiro Kusumi <kusumi.tomohiro@osnexus.com>
Closes#8408
Currently, zvol_rename_minors_impl() calls kmem_asprintf()
to allocate and initialize a string. This function is a thin
wrapper around the kernel's kvasprintf() and does not call
into the SPL's kmem tracking code when it is enabled. However,
this function frees the string with the tracked kmem_free()
instead of the untracked strfree(), which causes the SPL
kmem tracking code to believe that the function is attempting
to free memory it never allocated, triggering an ASSERT. This
patch simply corrects this issue.
Reviewed by: Matt Ahrens <mahrens@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tom Caputi <tcaputi@datto.com>
Closes#8307
As a result of the changes made in 8585, it's possible for an excessive
amount of vdev flush commands to be issued under some workloads.
Specifically, when the workload consists of mostly async write activity,
interspersed with some sync write and/or fsync activity, we can end up
issuing more flush commands to the underlying storage than is actually
necessary. As a result of these flush commands, the write latency and
overall throughput of the pool can be poorly impacted (latency
increases, throughput decreases).
Currently, any time an lwb completes, the vdev(s) written to as a result
of that lwb will be issued a flush command. The intenion is so the data
written to that vdev is on stable storage, prior to communicating to any
waiting threads that their data is safe on disk.
The problem with this scheme, is that sometimes an lwb will not have any
threads waiting for it to complete. This can occur when there's async
activity that gets "converted" to sync requests, as a result of calling
the zil_async_to_sync() function via zil_commit_impl(). When this
occurs, the current code may issue many lwbs that don't have waiters
associated with them, resulting in many flush commands, potentially to
the same vdev(s).
For example, given a pool with a single vdev, and a single fsync() call
that results in 10 lwbs being written out (e.g. due to other async
writes), that will result in 10 flush commands to that single vdev (a
flush issued after each lwb write completes). Ideally, we'd only issue a
single flush command to that vdev, after all 10 lwb writes completed.
Further, and most important as it pertains to this change, since the
flush commands are often very impactful to the performance of the pool's
underlying storage, unnecessarily issuing these flush commands can
poorly impact the performance of the lwb writes themselves. Thus, we
need to avoid issuing flush commands when possible, in order to acheive
the best possible performance out of the pool's underlying storage.
This change attempts to address this problem by changing the ZIL's logic
to only issue a vdev flush command when it detects an lwb that has a
thread waiting for it to complete. When an lwb does not have threads
waiting for it, the responsibility of issuing the flush command to the
vdevs involved with that lwb's write is passed on to the "next" lwb.
It's only once a write for an lwb with waiters completes, do we issue
the vdev flush command(s). As a result, now when we issue the flush(s),
we will issue them to the vdevs involved with that specific lwb's write,
but potentially also to vdevs involved with "previous" lwb writes (i.e.
if the previous lwbs did not have waiters associated with them).
Thus, in our prior example with 10 lwbs, it's only once the last lwb
completes (which will be the lwb containing the waiter for the thread
that called fsync) will we issue the vdev flush command; all of the
other lwbs will find they have no waiters, so they'll pass the
responsibility of the flush to the "next" lwb (until reaching the last
lwb that has the waiter).
Porting Notes:
* Reconciled conflicts with the fastwrite feature.
Authored by: Prakash Surya <prakash.surya@delphix.com>
Reviewed by: Matt Ahrens <matt@delphix.com>
Reviewed by: Brad Lewis <brad.lewis@delphix.com>
Reviewed by: Patrick Mooney <patrick.mooney@joyent.com>
Reviewed by: Jerry Jelinek <jerry.jelinek@joyent.com>
Approved by: Joshua M. Clulow <josh@sysmgr.org>
Ported-by: Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
OpenZFS-issue: https://www.illumos.org/issues/9962
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/545190c6Closes#8188
The ZFS range locking code in zfs_rlock.c/h depends on ZPL-specific
data structures, specifically znode_t. However, it's also used by
the ZVOL code, which uses a "dummy" znode_t to pass to the range
locking code.
We should clean this up so that the range locking code is generic
and can be used equally by ZPL and ZVOL, and also can be used by
future consumers that may need to run in userland (libzpool) as
well as the kernel.
Porting notes:
* Added missing sys/avl.h include to sys/zfs_rlock.h.
* Removed 'dbuf is within the locked range' ASSERTs from dmu_sync().
This was needed because ztest does not yet use a locked_range_t.
* Removed "Approved by:" tag requirement from OpenZFS commit
check to prevent needless warnings when integrating changes
which has not been merged to illumos.
* Reverted free_list range lock changes which were originally
needed to defer the cv_destroy() which was called immediately
after cv_broadcast(). With d2733258 this should be safe but
if not we may need to reintroduce this logic.
* Reverts: The following two commits were reverted and squashed in
to this change in order to make it easier to apply OpenZFS 9689.
- d88895a0, which removed the dummy znode from zvol_state
- e3a07cd0, which updated ztest to use range locks
* Preserved optimized rangelock comparison function. Preserved the
rangelock free list. The cv_destroy() function will block waiting
for all processes in cv_wait() to be scheduled and drop their
reference. This is done to ensure it's safe to free the condition
variable. However, blocking while holding the rl->rl_lock mutex
can result in a deadlock on Linux. A free list is introduced to
defer the cv_destroy() and kmem_free() until after the mutex is
released.
Authored by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed by: Serapheim Dimitropoulos <serapheim.dimitro@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Brad Lewis <brad.lewis@delphix.com>
Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>
OpenZFS-issue: https://illumos.org/issues/9689
OpenZFS-commit: https://github.com/openzfs/openzfs/pull/680
External-issue: DLPX-58662
Closes#7980
Currently, when unmounting a filesystem, ZFS will only wait for
a txg sync if the dataset is dirty and not readonly. However, this
can be problematic in cases where a dataset is remounted readonly
immediately before being unmounted, which often happens when the
system is being shut down. Since encrypted datasets require that
all I/O is completed before the dataset is disowned, this issue
causes problems when write I/Os leak into the txgs after the
dataset is disowned, which can happen when sync=disabled.
While looking into fixes for this issue, it was discovered that
dsl_dataset_is_dirty() does not return B_TRUE when the dataset has
been removed from the txg dirty datasets list, but has not actually
been processed yet. Furthermore, the implementation is comletely
different from dmu_objset_is_dirty(), adding to the confusion.
Rather than relying on this function, this patch forces the umount
code path (and the remount readonly code path) to always perform a
txg sync on read-write datasets and removes the function altogether.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tom Caputi <tcaputi@datto.com>
Closes#7753Closes#7795
The following patch introduces a few statistics on reads and writes
grouped by dataset. These statistics are implemented as kstats
(backed by aggregate sums for performance) and can be retrieved by
using the dataset objset ID number. The motivation for this change is
to provide some preliminary analytics on dataset usage/performance.
Reviewed-by: Richard Elling <Richard.Elling@RichardElling.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Signed-off-by: Serapheim Dimitropoulos <serapheim@delphix.com>
Closes#7705
Added support for the bops->check_events() interface which was
added in the 2.6.38 kernel to replace bops->media_changed().
Fully implementing this functionality allows the volume resize
code to rely on revalidate_disk(), which is the preferred
mechanism, and removes the need to use check_disk_size_change().
In order for bops->check_events() to lookup the zvol_state_t
stored in the disk->private_data the zvol_state_lock needs to
be held. Since the check events interface may poll the mutex
has been converted to a rwlock for better concurrently. The
rwlock need only be taken as a writer in the zvol_free() path
when disk->private_data is set to NULL.
The configure checks for the block_device_operations structure
were consolidated in a single kernel-block-device-operations.m4
file.
The ZFS_AC_KERNEL_BDEV_BLOCK_DEVICE_OPERATIONS configure checks
and assoicated dead code was removed. This interface was added
to the 2.6.28 kernel which predates the oldest supported 2.6.32
kernel and will therefore always be available.
Updated maximum Linux version in META file. The 4.17 kernel
was released on 2018-06-03 and ZoL is compatible with the
finalized kernel.
Reviewed-by: Boris Protopopov <boris.protopopov@actifio.com>
Reviewed-by: Sara Hartse <sara.hartse@delphix.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#7611
As of https://github.com/torvalds/linux/commit/fb6d47a, get_disk()
is now get_disk_and_module(). Add a configure check to determine
if we need to use get_disk_and_module().
Reviewed-by: loli10K <ezomori.nozomu@gmail.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Closes#7264
Currently, ZIL claiming dirties objsets which causes
dsl_pool_sync() to attempt to perform user accounting on
them. This causes problems for encrypted datasets that were
raw received before the system went offline since they
cannot perform user accounting until they have their keys
loaded. This triggers an ASSERT in zio_encrypt(). Since
encryption was added, the code now depends on the fact that
data should only be written when objsets are owned. This
patch adds a check in dmu_objset_do_userquota_updates()
to ensure that useraccounting is only done when the objsets
are actually owned for write. As part of this work, the
zfsvfs and zvol code was updated so that it no longer lies
about owning objsets readonly.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tom Caputi <tcaputi@datto.com>
Closes#6916Closes#7163
The on-disk format for encrypted datasets protects not only
the encrypted and authenticated blocks themselves, but also
the order and interpretation of these blocks. In order to
make this work while maintaining the ability to do raw
sends, the indirect bps maintain a secure checksum of all
the MACs in the block below it along with a few other
fields that determine how the data is interpreted.
Unfortunately, the current on-disk format erroneously
includes some fields which are not portable and thus cannot
support raw sends. It is not possible to easily work around
this issue due to a separate and much smaller bug which
causes indirect blocks for encrypted dnodes to not be
compressed, which conflicts with the previous bug. In
addition, the current code generates incompatible on-disk
formats on big endian and little endian systems due to an
issue with how block pointers are authenticated. Finally,
raw send streams do not currently include dn_maxblkid when
sending both the metadnode and normal dnodes which are
needed in order to ensure that we are correctly maintaining
the portable objset MAC.
This patch zero's out the offending fields when computing
the bp MAC and ensures that these MACs are always
calculated in little endian order (regardless of the host
system's byte order). This patch also registers an errata
for the old on-disk format, which we detect by adding a
"version" field to newly created DSL Crypto Keys. We allow
datasets without a version (version 0) to only be mounted
for read so that they can easily be migrated. We also now
include dn_maxblkid in raw send streams to ensure the MAC
can be maintained correctly.
This patch also contains minor bug fixes and cleanups.
Reviewed-by: Jorgen Lundman <lundman@lundman.net>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Signed-off-by: Tom Caputi <tcaputi@datto.com>
Closes#6845Closes#6864Closes#7052
Authored by: Prakash Surya <prakash.surya@delphix.com>
Reviewed by: Brad Lewis <brad.lewis@delphix.com>
Reviewed by: Matt Ahrens <mahrens@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Approved by: Dan McDonald <danmcd@joyent.com>
Ported-by: Prakash Surya <prakash.surya@delphix.com>
Problem
=======
The current implementation of zil_commit() can introduce significant
latency, beyond what is inherent due to the latency of the underlying
storage. The additional latency comes from two main problems:
1. When there's outstanding ZIL blocks being written (i.e. there's
already a "writer thread" in progress), then any new calls to
zil_commit() will block waiting for the currently oustanding ZIL
blocks to complete. The blocks written for each "writer thread" is
coined a "batch", and there can only ever be a single "batch" being
written at a time. When a batch is being written, any new ZIL
transactions will have to wait for the next batch to be written,
which won't occur until the current batch finishes.
As a result, the underlying storage may not be used as efficiently
as possible. While "new" threads enter zil_commit() and are blocked
waiting for the next batch, it's possible that the underlying
storage isn't fully utilized by the current batch of ZIL blocks. In
that case, it'd be better to allow these new threads to generate
(and issue) a new ZIL block, such that it could be serviced by the
underlying storage concurrently with the other ZIL blocks that are
being serviced.
2. Any call to zil_commit() must wait for all ZIL blocks in its "batch"
to complete, prior to zil_commit() returning. The size of any given
batch is proportional to the number of ZIL transaction in the queue
at the time that the batch starts processing the queue; which
doesn't occur until the previous batch completes. Thus, if there's a
lot of transactions in the queue, the batch could be composed of
many ZIL blocks, and each call to zil_commit() will have to wait for
all of these writes to complete (even if the thread calling
zil_commit() only cared about one of the transactions in the batch).
To further complicate the situation, these two issues result in the
following side effect:
3. If a given batch takes longer to complete than normal, this results
in larger batch sizes, which then take longer to complete and
further drive up the latency of zil_commit(). This can occur for a
number of reasons, including (but not limited to): transient changes
in the workload, and storage latency irregularites.
Solution
========
The solution attempted by this change has the following goals:
1. no on-disk changes; maintain current on-disk format.
2. modify the "batch size" to be equal to the "ZIL block size".
3. allow new batches to be generated and issued to disk, while there's
already batches being serviced by the disk.
4. allow zil_commit() to wait for as few ZIL blocks as possible.
5. use as few ZIL blocks as possible, for the same amount of ZIL
transactions, without introducing significant latency to any
individual ZIL transaction. i.e. use fewer, but larger, ZIL blocks.
In theory, with these goals met, the new allgorithm will allow the
following improvements:
1. new ZIL blocks can be generated and issued, while there's already
oustanding ZIL blocks being serviced by the storage.
2. the latency of zil_commit() should be proportional to the underlying
storage latency, rather than the incoming synchronous workload.
Porting Notes
=============
Due to the changes made in commit 119a394ab0, the lifetime of an itx
structure differs than in OpenZFS. Specifically, the itx structure is
kept around until the data associated with the itx is considered to be
safe on disk; this is so that the itx's callback can be called after the
data is committed to stable storage. Since OpenZFS doesn't have this itx
callback mechanism, it's able to destroy the itx structure immediately
after the itx is committed to an lwb (before the lwb is written to
disk).
To support this difference, and to ensure the itx's callbacks can still
be called after the itx's data is on disk, a few changes had to be made:
* A list of itxs was added to the lwb structure. This list contains
all of the itxs that have been committed to the lwb, such that the
callbacks for these itxs can be called from zil_lwb_flush_vdevs_done(),
after the data for the itxs is committed to disk.
* A list of itxs was added on the stack of the zil_process_commit_list()
function; the "nolwb_itxs" list. In some circumstances, an itx may
not be committed to an lwb (e.g. if allocating the "next" ZIL block
on disk fails), so this list is used to keep track of which itxs
fall into this state, such that their callbacks can be called after
the ZIL's writer pipeline is "stalled".
* The logic to actually call the itx's callback was moved into the
zil_itx_destroy() function. Since all consumers of zil_itx_destroy()
were effectively performing the same logic (i.e. if callback is
non-null, call the callback), it seemed like useful code cleanup to
consolidate this logic into a single function.
Additionally, the existing Linux tracepoint infrastructure dealing with
the ZIL's probes and structures had to be updated to reflect these code
changes. Specifically:
* The "zil__cw1" and "zil__cw2" probes were removed, so they had to be
removed from "trace_zil.h" as well.
* Some of the zilog structure's fields were removed, which affected
the tracepoint definitions of the structure.
* New tracepoints had to be added for the following 3 new probes:
* zil__process__commit__itx
* zil__process__normal__itx
* zil__commit__io__error
OpenZFS-issue: https://www.illumos.org/issues/8585
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/5d95a3aCloses#6566
Resolve new warnings and errors from cppcheck v1.80.
* [lib/libshare/libshare.c:543]: (warning)
Possible null pointer dereference: protocol
* [lib/libzfs/libzfs_dataset.c:2323]: (warning)
Possible null pointer dereference: srctype
* [lib/libzfs/libzfs_import.c:318]: (error)
Uninitialized variable: link
* [module/zfs/abd.c:353]: (error) Uninitialized variable: sg
* [module/zfs/abd.c:353]: (error) Uninitialized variable: i
* [module/zfs/abd.c:385]: (error) Uninitialized variable: sg
* [module/zfs/abd.c:385]: (error) Uninitialized variable: i
* [module/zfs/abd.c:553]: (error) Uninitialized variable: i
* [module/zfs/abd.c:553]: (error) Uninitialized variable: sg
* [module/zfs/abd.c:763]: (error) Uninitialized variable: i
* [module/zfs/abd.c:763]: (error) Uninitialized variable: sg
* [module/zfs/abd.c:305]: (error) Uninitialized variable: tmp_page
* [module/zfs/zpl_xattr.c:342]: (warning)
Possible null pointer dereference: value
* [module/zfs/zvol.c:208]: (error) Uninitialized variable: p
Convert the following suppression to inline.
* [module/zfs/zfs_vnops.c:840]: (error)
Possible null pointer dereference: aiov
Exclude HAVE_UIO_ZEROCOPY and HAVE_DNLC from analysis since
these macro's will never be defined until this functionality
is implemented.
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#6879
Fix compiler warnings in zdb. With these changes, FreeBSD can compile
zdb with all compiler warnings enabled save -Wunused-parameter.
usr/src/cmd/zdb/zdb.c
usr/src/cmd/zdb/zdb_il.c
usr/src/uts/common/fs/zfs/sys/sa.h
usr/src/uts/common/fs/zfs/sys/spa.h
Fix numerous warnings, including:
* const-correctness
* shadowing global definitions
* signed vs unsigned comparisons
* missing prototypes, or missing static declarations
* unused variables and functions
* Unreadable array initializations
* Missing struct initializers
usr/src/cmd/zdb/zdb.h
Add a header file to declare common symbols
usr/src/lib/libzpool/common/sys/zfs_context.h
usr/src/uts/common/fs/zfs/arc.c
usr/src/uts/common/fs/zfs/dbuf.c
usr/src/uts/common/fs/zfs/spa.c
usr/src/uts/common/fs/zfs/txg.c
Add a function prototype for zk_thread_create, and ensure that every
callback supplied to this function actually matches the prototype.
usr/src/cmd/ztest/ztest.c
usr/src/uts/common/fs/zfs/sys/zil.h
usr/src/uts/common/fs/zfs/zfs_replay.c
usr/src/uts/common/fs/zfs/zvol.c
Add a function prototype for zil_replay_func_t, and ensure that
every function of this type actually matches the prototype.
usr/src/uts/common/fs/zfs/sys/refcount.h
Change FTAG so it discards any constness of __func__, necessary
since existing APIs expect it passed as void *.
Porting Notes:
- Many of these fixes have already been applied to Linux. For
consistency the OpenZFS version of a change was applied if the
warning was addressed in an equivalent but different fashion.
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Prakash Surya <prakash.surya@delphix.com>
Authored by: Alan Somers <asomers@gmail.com>
Approved by: Richard Lowe <richlowe@richlowe.net>
Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>
OpenZFS-issue: https://www.illumos.org/issues/8081
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/843abe1b8aCloses#6787
generic_start_io_acct/generic_end_io_acct in the master
branch of the linux kernel requires that the request_queue
be provided.
Move the logic from freemem in the spl to arc_free_memory
in arc.c. Do this so we can take advantage of global_page_state
interface checks in zfs.
Upstream kernel replaced struct block_device with
struct gendisk in struct bio. Determine if the
function bio_set_dev exists during configure
and have zfs use that if it exists.
bio_set_dev https://github.com/torvalds/linux/commit/74d4699
global_node_page_state https://github.com/torvalds/linux/commit/75ef718
io acct https://github.com/torvalds/linux/commit/d62e26b
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Closes#6635
The portion of the zvol_replay_write() handler responsible for
replaying indirect log records for some reason never existed.
As a result indirect log records were not being correctly replayed.
This went largely unnoticed since the majority of zvol log records
were of the type WR_COPIED or WR_NEED_COPY prior to OpenZFS 7578.
This patch updates zvol_replay_write() to correctly handle these
log records and adds a new test case which verifies volume replay
to prevent any regression. The existing test case which verified
replay on filesystem was renamed slog_replay_fs.ksh for clarity.
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: loli10K <ezomori.nozomu@gmail.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#6603Closes#6615
Since OpenZFS 7578 (1b7c1e5) if we have a ZVOL with logbias=throughput
we will force WR_INDIRECT itxs in zvol_log_write() setting itx->itx_lr
offset and length to the offset and length of the BIO from
zvol_write()->zvol_log_write(): these offset and length are later used
to take a range lock in zillog->zl_get_data function: zvol_get_data().
Now suppose we have a ZVOL with blocksize=8K and push 4K writes to
offset 0: we will only be range-locking 0-4096. This means the
ASSERTion we make in dbuf_unoverride() is no longer valid because now
dmu_sync() is called from zilog's get_data functions holding a partial
lock on the dbuf.
Fix this by taking a range lock on the whole block in zvol_get_data().
Reviewed-by: Chunwei Chen <tuxoko@gmail.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: loli10K <ezomori.nozomu@gmail.com>
Closes#6238Closes#6315Closes#6356Closes#6477
This change incorporates three major pieces:
The first change is a keystore that manages wrapping
and encryption keys for encrypted datasets. These
commands mostly involve manipulating the new
DSL Crypto Key ZAP Objects that live in the MOS. Each
encrypted dataset has its own DSL Crypto Key that is
protected with a user's key. This level of indirection
allows users to change their keys without re-encrypting
their entire datasets. The change implements the new
subcommands "zfs load-key", "zfs unload-key" and
"zfs change-key" which allow the user to manage their
encryption keys and settings. In addition, several new
flags and properties have been added to allow dataset
creation and to make mounting and unmounting more
convenient.
The second piece of this patch provides the ability to
encrypt, decyrpt, and authenticate protected datasets.
Each object set maintains a Merkel tree of Message
Authentication Codes that protect the lower layers,
similarly to how checksums are maintained. This part
impacts the zio layer, which handles the actual
encryption and generation of MACs, as well as the ARC
and DMU, which need to be able to handle encrypted
buffers and protected data.
The last addition is the ability to do raw, encrypted
sends and receives. The idea here is to send raw
encrypted and compressed data and receive it exactly
as is on a backup system. This means that the dataset
on the receiving system is protected using the same
user key that is in use on the sending side. By doing
so, datasets can be efficiently backed up to an
untrusted system without fear of data being
compromised.
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Jorgen Lundman <lundman@lundman.net>
Signed-off-by: Tom Caputi <tcaputi@datto.com>
Closes#494Closes#5769
Acquire zv_suspend_lock on first open and last close only.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Boris Protopopov <boris.protopopov@actifio.com>
Closes#6342
At import time spa_import() calls zvol_create_minors() directly: with
the current implementation we have no way to avoid device node
creation when volmode=none.
Fix this by enforcing volmode=none directly in zvol_alloc().
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: loli10K <ezomori.nozomu@gmail.com>
Closes#6426
The volmode property may be set to control the visibility of ZVOL
block devices.
This allow switching ZVOL between three modes:
full - existing fully functional behaviour (default)
dev - hide partitions on ZVOL block devices
none - not exposing volumes outside ZFS
Additionally the new zvol_volmode module parameter can be used to
control the default behaviour.
This functionality can be used, for instance, on "backup" pools to
avoid cluttering /dev with unneeded zd* devices.
Original-patch-by: mav <mav@FreeBSD.org>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Ported-by: loli10K <ezomori.nozomu@gmail.com>
Signed-off-by: loli10K <ezomori.nozomu@gmail.com>
FreeBSD-commit: https://github.com/freebsd/freebsd/commit/dd28e6bbCloses#1796Closes#3438Closes#6233
On the single core machine the system may hang when the
spa_namespare_lock acquisition fails in the zvol_first_open
function. It returns -ERESTARTSYS error what causes the
endless loop in __blkdev_get function.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Signed-off-by: Arkadiusz Bubała <arkadiusz.bubala@open-e.com>
Closes#6283Closes#6312
Authored by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Prakash Surya <prakash.surya@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Approved by: Robert Mustacchi <rm@joyent.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Ported-by: Giuseppe Di Natale <dinatale2@llnl.gov>
The problem is that zfs_get_data() supplies a stale zgd_bp to
dmu_sync(), which we then nopwrite against.
zfs_get_data() doesn't hold any DMU-related locks, so after it
copies db_blkptr to zgd_bp, dbuf_write_ready() could change
db_blkptr, and dbuf_write_done() could remove the dirty record.
dmu_sync() then sees the stale BP and that the dbuf it not dirty,
so it is eligible for nop-writing.
The fix is for dmu_sync() to copy db_blkptr to zgd_bp after
acquiring the db_mtx. We could still see a stale db_blkptr,
but if it is stale then the dirty record will still exist and
thus we won't attempt to nopwrite.
OpenZFS-issue: https://www.illumos.org/issues/8378
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/3127742Closes#6293
GCC 7.1 with will warn when we're not checking the snprintf()
return code in cases where the buffer could be truncated. This
patch either checks the snprintf return code (where applicable),
or simply disables the warnings (ztest.c).
Reviewed-by: Chunwei Chen <david.chen@osnexus.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tony Hutter <hutter2@llnl.gov>
Closes#6253
Use zv_state_lock to protect all members of zvol_state structure, add
relevant ASSERT()s. Take zv_suspend_lock before zv_state_lock, do not
hold zv_state_lock across suspend/resume.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Boris Protopopov <boris.protopopov@actifio.com>
Closes#6226
Use queue_flag_set_unlocked() in zvol_alloc().
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Boris Protopopov <boris.protopopov@actifio.com>
Issue #6226
This continues what was started in
0eef1bde31 by fully converting zvols
to avoid unnecessary dnode_hold() calls. This saves a small amount
of CPU time and slightly improves latencies of operations on zvols.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Richard Yao <richard.yao@prophetstor.com>
Closes#6058
- After some ZIL changes 6 years ago zil_slog_limit got partially broken
due to zl_itx_list_sz not updated when async itx'es upgraded to sync.
Actually because of other changes about that time zl_itx_list_sz is not
really required to implement the functionality, so this patch removes
some unneeded broken code and variables.
- Original idea of zil_slog_limit was to reduce chance of SLOG abuse by
single heavy logger, that increased latency for other (more latency critical)
loggers, by pushing heavy log out into the main pool instead of SLOG. Beside
huge latency increase for heavy writers, this implementation caused double
write of all data, since the log records were explicitly prepared for SLOG.
Since we now have I/O scheduler, I've found it can be much more efficient
to reduce priority of heavy logger SLOG writes from ZIO_PRIORITY_SYNC_WRITE
to ZIO_PRIORITY_ASYNC_WRITE, while still leave them on SLOG.
- Existing ZIL implementation had problem with space efficiency when it
has to write large chunks of data into log blocks of limited size. In some
cases efficiency stopped to almost as low as 50%. In case of ZIL stored on
spinning rust, that also reduced log write speed in half, since head had to
uselessly fly over allocated but not written areas. This change improves
the situation by offloading problematic operations from z*_log_write() to
zil_lwb_commit(), which knows real situation of log blocks allocation and
can split large requests into pieces much more efficiently. Also as side
effect it removes one of two data copy operations done by ZIL code WR_COPIED
case.
- While there, untangle and unify code of z*_log_write() functions.
Also zfs_log_write() alike to zvol_log_write() can now handle writes crossing
block boundary, that may also improve efficiency if ZPL is made to do that.
Sponsored by: iXsystems, Inc.
Authored by: Alexander Motin <mav@FreeBSD.org>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Prakash Surya <prakash.surya@delphix.com>
Reviewed by: Andriy Gapon <avg@FreeBSD.org>
Reviewed by: Steven Hartland <steven.hartland@multiplay.co.uk>
Reviewed by: Brad Lewis <brad.lewis@delphix.com>
Reviewed by: Richard Elling <Richard.Elling@RichardElling.com>
Approved by: Robert Mustacchi <rm@joyent.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Richard Yao <ryao@gentoo.org>
Ported-by: Giuseppe Di Natale <dinatale2@llnl.gov>
OpenZFS-issue: https://www.illumos.org/issues/7578
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/aeb13acCloses#6191
When inheriting the "snapdev" property to we don't always call
zfs_prop_set_special(): this prevents device nodes from being created in
certain situations. Because "snapdev" is the only *special* property
that is also inheritable we need to call zfs_prop_set_special() even
when we're not reverting it to the received value ('zfs inherit -S').
Additionally, fix a NULL pointer dereference accidentally introduced in
5559ba0 that can be triggered when setting the "snapdev" property to
the value "hidden" twice.
Finally, add a new test case "zvol_misc_snapdev" to the ZFS Test Suite.
Reviewed by: Boris Protopopov <bprotopopov@hotmail.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: loli10K <ezomori.nozomu@gmail.com>
Closes#6131Closes#6175Closes#6176
Move kmem_free() so it's called for every error path: this is
preferred over making `dmu_object_info_t doi` local to accommodate
older kernels with limited stacks.
Reviewed by: Boris Protopopov <bprotopopov@hotmail.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Signed-off-by: loli10K <ezomori.nozomu@gmail.com>
Closes#6177
Added missing ida_simple_remove() in the error handling path.
Reviewed-by: Chunwei Chen <david.chen@osnexus.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Signed-off-by: Boris Protopopov <boris.protopopov@actifio.com>
Closes#6159Closes#6172
This reverts commit 959f56b993.
An issue was uncovered by the new zvol_misc_snapdev test case
which needs to be investigated and resolved.
Reviewed-by: loli10K <ezomori.nozomu@gmail.com>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#6174
Issue #6131
When inheriting the "snapdev" property to we don't always call
zfs_prop_set_special(): this prevents device nodes from being created in
certain situations. Because "snapdev" is the only *special* property
that is also inheritable we need to call zfs_prop_set_special() even
when we're not reverting it to the received value ('zfs inherit -S').
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: loli10K <ezomori.nozomu@gmail.com>
Closes#6131
The lock is designed to protect internal state of zvol_state_t and
to avoid taking spa_namespace_lock (e.g. in dmu_objset_own() code path)
while holding zvol_stat_lock. Refactor the code accordingly.
Signed-off-by: Boris Protopopov <boris.protopopov@actifio.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes#3484Closes#6065Closes#6134
Fix lock order inversion with zvol_open() as it did not account
for use of zvols as vdevs. The latter use cases resulted in the
lock order inversion deadlocks that involved spa_namespace_lock
and bdev->bd_mutex.
Signed-off-by: Boris Protopopov <boris.protopopov@actifio.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Issue #6065
Issue #6134
